1. Field of the Invention
The present invention relates to a scan driver and a driving method thereof. More particularly, the present invention relates to a scan driver which is capable of being driven with a small number of clock signals, and a driving method thereof.
2. Description of the Related Art
Currently, various flat panel displays which can reduce the weight and the volume which are drawbacks of the cathode ray tube have been developed. As flat panel displays, there are a liquid crystal display (LCD), a field emission display, a plasma display panel (PDP) and an organic light emitting diode OLED.
The flat panel display includes a display panel consisting of a plurality of pixels arranged in a matrix format. The display panel includes a plurality of scan lines in a row direction and a plurality of data lines in a column direction, and the plurality of scan lines and the plurality of data lines intersect. The plurality of pixels are driven by scan signals and data signals transmitted through the corresponding scan lines and data lines.
The flat panel display is classified into a passive matrix light emitting display device and an active matrix light emitting display device according to the driving method thereof. Among them, the active matrix type, which selectively turns on/off the pixels, is mainly used in terms of resolution, contrast, and operation speed.
The active matrix organic light emitting diode (OLED) display writes a data signal in synchronization with the time that a scan signal is transmitted to a pixel. The scan signal may be transmitted to the scan line in a forward direction or a backward direction according to the arrangement of the scan line. As described above, the scan driver functions as a shift register for sequentially driving scan signals.
Recently, as the size of display panels has increased and the organic light emitting diode (OLED) display for displaying a 3D image has been developed, high speed of the scan driver has been required. To drive a panel of the active matrix type organic light emitting diode (OLED) display of a large size, the scan driver must drive a large load and duty control must be possible in order to minimize a motion blur. Also, to display a 3D image, it is preferable that the scan driver be driven with simultaneous light emission and a high speed of more than 240 Hz.
The above information disclosed in this Background section is only for enhancement of an understanding of the background of the invention, and therefore it may contain information which does not form the prior art which is already known in this country to a person of ordinary skill in the art.